This invention relates generally to conveyor belt systems for moving granular material such as sand, gravel, crushed rock, etc., and, more particularly, to skirtboards for use in retaining such granular material on a conveyor belt.
Conveyor belts are commonly used for transporting a variety of granular materials. These belts are typically constructed of a rubber material, and they move over numerous supporting rollers. The side edges of such conveyor belts may be tilted or cupped slightly upwardly, but it is still necessary to provide rubber skirtboards at the side edges of these belts in order to prevent the granular material conveyed thereon from spilling off the side of the belt.
These skirtboards must be made of a rubber material because the bottom edge of each skirtboard is in contact with the upper surface of the belt to provide a positive seal between the skirtboard and the belt. A metal or wooden skirtboard would damage the conveyor belt as it moves relative to the stationary skirtboards.
The skirtboards are supported by the conveyor steel frame or skirt plate, which extends downwardly to within several inches of the conveyor belt. It is important to avoid contact between the steel skirt plates and the belt in order to prevent damage to the belt.
The rubber skirtboards are typically constructed of softer rubber than that of the rubber conveyor belts themselves. Thus, the lower edges of the skirtboards contact the upper surface of the conveyor belt and are permitted to wear away without damaging the conveyor belt itself.
The skirtboard is typically provided in widths of about 4 to 10 inches and in thicknesses of 5/16-inch to more than one inch. It is also typically provided in 50-foot rolls, which can be cut to a desired length.
A skirtboard clamp is used to attach the upper portion of the skirtboard to the skirt plate and to apply pressure to the outside of the skirtboard in opposition to the pressure of the material being conveyed on the belt. As the lower edge of the skirtboard wears away, the clamps must be loosened to enable the skirtboard to be lowered to be closer to the conveyor belt.
Various types of conveyor belt skirtboard clamp systems are known in the prior art, representative of which are those described in U.S. Pat. Nos. 3,989,137, 4,204,595, 4,436,446, 5,048,669, 5,154,280, and 5,267,642. These prior art systems are in various respects cumbersome, difficult to use, and ineffective in applying the required pressure to the outer surface of the skirtboard. For example, many prior art clamping systems are of flimsy construction and utilize a number of components. Since the areas of a conveyor requiring the use of skirtboard rubber are generally dusty, dirty, wet, and difficult to access, the bolt and nut tightening systems employed in many skirtboard clamp systems are susceptible to rusting and thread-plugging, making their required periodic adjustment inconvenient and time consuming.
It would therefore be advantageous to provide a compact clamp system for use with conveyor belt skirtboards that utilizes a minimum number of parts and that is easy to adjust, even if positioned in areas that are difficult to access. In accordance with two illustrated embodiments of the present invention, a base member is attached to the steel support plate of a conventional conveyor. A stationary support member having a downwardly extending leg is fixedly attached to the base member, and a depending pressure bar assembly is hingedly attached to the support member. A wedge pin assembly is fixedly attached to the downwardly extending leg of the support member to releasably apply an inward force to the pressure bar assembly to urge it against a conveyor belt skirtboard.